<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container {
            display: flex;


            border: 1px solid black;
            flex-wrap: wrap;
        }

        .container div {
            margin: 5px;
            padding: 5px;
            width: 500px;
            height: 600px;
            border: 1px solid black;
        }

        .container div:nth-child(1) {}

        .container div:nth-child(2) {
            flex: 1;

        }
    </style>
</head>

<body>
    <header class="container">
        <div>这是1</div>
        <div></div>
        <div>这是2</div>
    </header>
    <script>

    </script>
</body>

</html>